Electrocatalysts, supported on carbon nanotubes (CNTs) were synthesized by two steps. In the first step, raw CNTs were refluxed with different concentrations of nitric acid, and in the second, metal precursors were attached to functionalized CNT surface with reducing agents. The concentration of nitric acid is important because oxidation introduces the functionality of the surface, which determines the morphology of the catalysts anchored on the support. (C) 2004 Elsevier Ltd. All rights reserved.